1. Field of Invention
The present invention relates to a method for protecting aluminum nitride from moisture and, more particularly, to a method for protecting aluminum nitride from moisture via using calcium silicate and dodecylamine of which the hydrophilism, thermal stability and thermal conductivity make the aluminum nitride moisture-proof and not vulnerable to deterioration so that the stability of the aluminum nitride is improved.
2. Related Prior Art
Solid materials include metals, ceramics, polymers and composites. The ceramics include precision ceramics. The precision ceramics exhibit mechanical strength, stability at high temperature, wear-resistance and erosion-resistance. Some of the precision ceramics even exhibit conductivity at high temperature, isolation, piezoelectricity and photoconductivity. Hence, the precision ceramics are deemed essential in science and technology.
Aluminum nitride is an important precision ceramic material. Aluminum nitride is highly thermally conductive as its heat transfer coefficient reaches 170 W/mK. Moreover, aluminum nitride is electrically isolative, mechanically strong, refractory and vibration-resistant. Hence, aluminum nitride can be used to make a substrate for use in a high-power electronic device.
A conventional process for making an aluminum nitride substrate includes the steps of providing aluminum nitride powder, molding, sintering and finishing. Each of the steps of the process influences the quality of the aluminum nitride substrate. Hence, the process for making the aluminum nitride substrate must be chosen carefully.
An aluminum nitride substrate radiates heat more than 7 times better than a substrate made of sapphire. The life of an aluminum nitride substrate reaches 6000 to 7000 hours. However, aluminum nitride easily reacts with oxygen. Therefore, in a hot or wet environment, the aluminum nitride on the surface of an aluminum nitride substrate easily reacts with oxygen and water to produce aluminum oxide. Thus, the purity of the aluminum nitride substrate is reduced, and the performance regarding the heat radiation is reduced.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.